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European Journal of Radiology 81 (2012) e123–e125

Contents lists available at ScienceDirect

European Journal of Radiology

  j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / e j r a d

The effect of nuchal cord on nuchal fold thickness measured in the secondtrimester

Esra Özkavukcu ∗, Nuray Haliloglu

 Ankara University School of Medicine, Turkey

a r t i c l e i n f o

 Article history:Received 30 November 2010Accepted 28 December 2010

Keywords:Nuchal cordNuchal skin fold thicknessUltrasound

a b s t r a c t

Purpose: To find out whether nuchal cord causes an effect on the nuchal skin fold thickness (NFT) mea-

surements, or not.Patients and methods: A total of 242 fetuses with normal outcomes that had undergone detailed secondtrimester US scan between 18 and 24 weeks of gestation were included in the study. NFT measurementswere made on axial cranial US images passing through the cerebellum and cavum septi pellucidum.To detect nuchal cord, color Doppler imaging was performed on the axial views of the fetal neck. Toinvestigate the differences in NFT measurements of the fetuses with or without nuchal cord, statisticalanalysis was performed using Mann–Whitney test. P < 0.05 was considered statistically significant.Results: Thestudygroupwas divided into twogroups: nuchal cord (+)(n: 26) and nuchalcord(−) (n: 216)fetuses. MeanNFT measurements were4.66±0.64mmand4.36±0.79mmfornuchalcord(+)andnuchalcord(−) fetuses, respectively. MedianNFT measurement fornuchal cord (+)fetuses was4.6 mm, whereasit was 4.4 mm for nuchal cord (−) fetuses. Statistically significant difference was denoted between twogroups, in terms of NFT measurements (P =0.049).Conclusion: NFT measurements of fetuses with nuchal cord are higher than the NFT measurements of fetuses without nuchal cord. One can conclude that the nuchal cord (+) fetuses with no other anomaliesbutincreased NFTshould be re-scanned to seeif theincreased NFTresolvesin theabsence of nuchal cord.

© 2011 Elsevier Ireland Ltd. All rights reserved.

1. Introduction

“Nuchal cord” or so-called “cord around neck” is a frequentincidental finding during pregnancy [1–3]. The term “nuchal cord”infers to the umbilical cord that encircles the fetal neck. Its inci-dence is controversial, probably depending on the gestational age[1] and the ultrasound (US) method used (2D vs. 3D) [3]. Nuchalcord is generally accepted as a benign finding [2].

The aim of this study was to find out whether this benign con-dition, i.e. nuchal cord causes an effect on the nuchal skin foldthickness(NFT) measured in thesecond trimesterof thepregnancy,

or not.

2. Patients and methods

Study group consisted of 242 pregnant women who referredto the radiology department for detailed second trimester US scan

∗ Corresponding author at: Ankara Üniversitesi Tıp Fakültesi Cebeci Hastanesi,Radyoloji Bölümü, 06100, Dikimevi, Ankara, Turkey. Tel.: +90 312 5956781.

E-mail addresses: eozkavukcu@gmail.com (E. Özkavukcu),nurayunsal2@hotmail.com (N. Haliloglu).

between November 2009 and February 2010. All US examinationswereperformedbetween18and24weeksofgestation,bythesameobserver. Only singleton pregnancies were included in the study.Fetuses with enlarged NFT, or major congenital anomalies werenot enrolled in the study either. Fetuses with normal US scans, andnormal physical examinations right after birth were accepted asnormal and included in the study.

All US examinations were performed using a SSA 770A ultra-sound system (Toshiba, Tokyo, Japan) with a 3.5MHz curvilineartransducer. During US scan,NFT measurements weremadeon axialcranial US images passing through the cerebellum and cavum septi

pellucidum. NFT was measured from the outside of the externaltable of the occipital bone to the outer edge of outlying skin. Toincrease the accuracy of the measurement, NFT was measured atleasttwo times. Then, theoptimum images withthe measurementswere reviewed and the maximum NFT measurement was recordedas the final one.

During all US scans, special attention was paid for the presenceof nuchal cord. An umbilical cord completely encircling the fetalneck was accepted as nuchal cord. To detect nuchal cord, colorDoppler or dynamic flow imaging were performed on the axialviews of the fetal neck. Once nuchal cord was confirmed, NFT wasalways measured above the level of nuchal cord (Fig. 1).

0720-048X/$ – see front matter © 2011 Elsevier Ireland Ltd. All rights reserved.

doi:10.1016/j.ejrad.2010.12.090

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e124 E. Özkavukcu, N. Halilo˘  glu / European Journal of Radiology 81 (2012) e123–e125

Fig. 1. (a–c) Sagittal (a) and axial (b) plane color Doppler US views of a fetus with agestational ageof 22weeksand 4 days show thedoubleloopnuchal cord aroundthefetalneck (arrows).On theaxial transcerebellarUS view(c) of thesame patient pass-ing through the cavum septum pellucidum and thalami, nuchal skin fold thicknessis measured as 5.6 mm (arrowheads).

To investigate the differences in NFT measurements of thefetuses with or without nuchal cord, statistical analysis was per-formed with SPSS version 15.0 (SPSS Inc., Chicago, IL, USA) usingMann–Whitney test. P < 0.05 was considered statistically signifi-cant.

3. Results

Among all fetuses enrolled in thestudy (n: 242), 26 fetuses withnuchal cord were detected (10.74%). The study group was dividedinto two groups: nuchalcord(+) (n:26)andnuchalcord(−) (n:216)fetuses. All nuchal cord (+) fetuses had a single loop around theirneck, except the two fetuses that had double loops. NFT measure-ments ranged between 3.5–6mm and 2.3–6mm, in nuchal cord (+)andnuchal cord (−) fetuses, respectively. MeanNFT measurementswere 4.66±0.64mm and 4.36±0.79mm for nuchal cord (+) andnuchal cord (−) fetuses, respectively. Median NFT measurementfor nuchal cord (+) fetuses was 4.6mm, whereas it was 4.4mm fornuchal cord (−) fetuses.

Using Mann–Whitney test, statistically significant differencewas denoted between nuchal cord (+) and nuchal cord (−) groups,in terms of NFT measurements (P = 0.049).

4. Discussion

Thanksto the improvement in US machinesand thewidespreadusage of US, the antenatal detection rate of nuchal cord is increas-ing progressively. However, the detection of nuchal cord by USscans can cause anxiety in both the expectant mother and the doc-tor [2]. Despite the older studies which demonstrated associationsbetween nuchal cord and maternal or neonatal morbidity, recentstudies showed that the nuchal cord is not associated with adverseperinatal outcome and fetal compromise [1,2]. Thus, informing thepatient about this probably negligible US finding is still debatable[2].

Althoughthe antenatal incidenceof nuchal cordis controversial,

one well-known factor influencing its incidence is the gestationalage [1]. Clapp et al., showed an incidence of nuchal cord rangingbetween 12 and 37%, rising with advancing gestational age [1].Another possible major factor that may influence the incidence of nuchal cord is the method used for the US scan [3]. For example, intheir study group consisting of fetuses between 10 and 14 weeksof gestational age, Schaefer et al. reported a nuchal cord incidenceof 8% using two dimensional US [4], whereas Tepper et al, reporteda much higher incidence between 13 and 16 weeks [3]. We usedtwo-dimensional US, combined with color Doppler imaging, andour study group consisted of fetuses between 18 and 24 weeks of gestational age. Considering the US method we used and the ges-tational age of our patients, the incidence of nuchal cord (10.74%)that we found is quite consistent with the previous reports. In our

opinion,realizingthe presence of a nuchal cord during routine two-dimensional US scanning is not that easy, unless special attentionis paid and color Doppler imaging is used.

Nuchal cord can lead to an increase in the nuchal translucency(NT) and NFT measurements, in the first and second trimesters of the pregnancy, respectively [4–7]. Nuchal cord can cause indenta-tion of the fetal skin, in this way it can cause displacement of thefluid in the fetal neck leading to alteration of the NT measurement[5]. Other possiblemechanisms thatmightexplainthe increasedNTmeasurements of nuchal cord (+) fetuses are the alterations in thelymphatic drainageand transientheartfailuredueto umbilicalcordcompression [6]. Maymon et al. claimed that the nuchal cord couldbe the cause of the transient increased NT thickness in their twocases, with no other fetal anatomical or chromosomal anomalies

[6]. Schaefer et al. and Scheier et al. both investigated the impor-

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tance of nuchal cord in the measurement of NT in first trimester[4,5]. Schaefer et al. pointed out that if the umbilical cord is mea-sured togetherwith NT, this addsa meanof 0.8 mmto the actualNTmeasurement.Therefore, the nuchalcord shouldnot be included inNT measurements, so as not to lead a false-positive diagnosis andunnecessary invasive testing [4]. On the other hand, Scheier et al.claim that the nuchal cord causes unpredictable changes in the NTmeasurement and “true” NT cannot be predicted accurately whenthe NT is measured in the presence of a nuchal cord [5]. They sug-gest repeating the US scan after a few hours, to measure the “true”NT in the absence of nuchalcord [5]. In this study,we didnot repeatthe examination to see if the NFT measurement changes when thenuchal cord is gone. In fact, it would truly be wise to repeat theexamination in the fetuses with enlarged NT or NFT accompaniedby nuchal cord.

Lee et al., studied the effects of gestational age, cephalic index,fetal presentation, and nuchal cord on NFT measurements. Theyformulated a regression equation on the basis of these variables,to calculate the actual NFT. They showed that the fetuses withnuchalcord has a meanNFT of 5.92(±1.03), whereas fetuses with-out nuchal cord has a mean NFT of 4.85 (±1.29), with a P value of 0.0001 [7]. This statistical difference is quite higher than the differ-ence we found in our study. Our US scans were done by a single,

experienced observer, and although nuchal cord can increase NFTmeasurements, we do not think that this effect is that strong.

5. Conclusions

NFT measurement is an important US parameter in the antena-taldiagnosis of Downsyndrome. Thepresenceof nuchalcordmightlead to an increasedNFT. Considering that the nuchal cord is a quite

frequent US finding, for the fetuses with increased NFT measure-ments, color Doppler imaging of the fetal neck should be done, inorder to exclude nuchal cord. Although fetuses with increased NFTmeasurements were not enrolled in this study, one can concludethat in the presence of nuchal cord, fetuses with no other anoma-lies butincreased NFTmeasurements shouldbe re-scanned to seeif theincreased NFTresolvesin the absence of nuchalcord. This mightreduce the false-positivescreening results that lead to unnecessaryinvasive testing.

Conflict of interest

There are no conflict of interests.

References

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[3] Tepper R, Kidron D, Aviram R, Markovitch O, Hershkovitz R. High incidenceof cord entanglement during early pregnancy detected by three-dimensionalsonography. Am J Perinatol 2009;26(5):379–82.

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